Fluid Meter With Varying Measuring Tube Wall Thickness
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Solution Overview
Problem
Existing fluid meters face limitations in measurement accuracy due to the weakening of bulk acoustic waves with each reflection on the measuring tube wall, leading to reduced signal strength, especially for low fluid flows.
Innovation Solution
The measuring tube wall has varying thicknesses, with a thinner first wall thickness for efficient coupling at the transmitter and receiver, and a thicker second wall thickness at reflection points to minimize energy transfer into the wall, allowing bulk waves to travel longer distances with maintained signal strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the measuring tube wall has a constant thickness optimized for coupling surface waves into the fluid, then the coupling efficiency at transmitter and receiver is improved, but the signal strength decreases with each reflection due to energy transfer into the wall
Solution Approach 1:
The measuring tube wall is designed with spatially varying thickness: a first wall thickness in the coupling areas (transmitter and receiver) optimized for efficient surface wave-to-bulk wave conversion, and a second, different wall thickness in the reflection areas that minimizes energy transfer into the wall. This local differentiation allows each section to perform its specific function optimally without compromising the other.
Solution Approach 2:
The measuring tube wall is segmented into functionally distinct sections: coupling sections at the transmitter and receiver locations with one wall thickness, and reflection sections at intermediate points with a different wall thickness. This segmentation enables independent optimization of coupling efficiency and reflection characteristics without mutual interference.
2Measurement precision
If the measuring section length is increased to improve measurement accuracy for low fluid flows, then the bulk wave travels a longer distance through the fluid, but the signal becomes much weaker due to multiple reflections on the wall
Solution Approach 1:
Different sections of the measuring tube wall are given different thicknesses tailored to their specific functions: coupling sections for efficient wave conversion and reflection sections for minimizing energy loss. This allows the bulk wave to traverse longer distances through the fluid with maintained signal strength, as energy transfer into the wall is minimized at reflection points.
3Use of energy by moving object
If the wall thickness is reduced to improve coupling efficiency, then more energy is transferred into the measuring tube wall at reflection points, causing the bulk wave to become weaker
Solution Approach 1:
The wall thickness is optimized locally for each functional region: thinner in coupling areas to maximize energy transfer from surface waves to bulk waves, and thicker in reflection areas to minimize parasitic coupling into the wall. This spatial variation in thickness resolves the contradiction between coupling efficiency and energy conservation.
Solution Approach 2:
The tube wall is divided into coupling zones and reflection zones with different thicknesses. This segmentation allows the system to achieve high coupling efficiency where needed while preventing energy loss at reflection points, thereby maintaining bulk wave strength over long measurement paths.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enables a longer measuring area with improved signal strength, particularly beneficial for low fluid flows, by optimizing the reflection points and reducing energy loss at the measuring tube wall, thereby enhancing measurement accuracy.
Implementation Method 1
surface acoustic waves (SAW) are excited in the waveguide, the type and frequency of which are chosen such that a partial coupling-out into the fluid in direct contact with the waveguide is effected
Implementation Method 2
Some of the surface acoustic waves in the waveguide are thus coupled into the fluid and pass through it as longitudinal bulk acoustic waves
Implementation Method 3
On their way through the fluid, the acoustic waves are reflected at least once on an opposite wall of the fluid channel
Implementation Method 4
with the result that they strike the waveguide again, where some of these bulk waves are coupled into the waveguide again
Implementation Method 5
the energy transfer to the measuring tube wall is decisively influenced by the choice of the wall thickness. In order for less energy to be transferred to the measuring tube wall at a reflection point of the bulk wave, the second wall thickness present at the reflection point is chosen differing from the first wall thickness
Data Source
AI summary
A fluid meter has a measuring tube which has a fluid channel allowing a fluid (F) to flow through and which has a measuring section in which at least one area of a measuring tube wall is formed as a waveguide for surface acoustic waves, which forms an interface with the fluid (F), and at least one transmitter for exciting acoustic waves in the waveguide as well as at least one receiver for receiving acoustic waves from the waveguide, wherein acoustic waves excited by the transmitter can propagate through the fluid (F) as a bulk wave (V) and the bulk wave (V) has at least one reflection point (IP) on the measuring tube wall. The measuring tube wall has a first wall thickness (T1) in the area of the transmitter and in the area of the receiver and has a second wall thickness (T2) which differs from the first wall thickness (T1) in the area of all reflection points (IP) of the bulk wave (V).